A. Field of the Invention
The present invention relates to tools and implements such as hoes of the type which are typically provided with a long handle for grasping and manipulation by an individual person. More particularly, the invention relates to an improved concrete mixing hoe which facilitates the mixing of dry concrete pre-mix with water to form a viscous slurry suitable for pouring into a construction form or other such structure construction applications.
B. Description of Background Art
Dry concrete xe2x80x9cpre-mixxe2x80x9d consists of a dry mixture of Portland cement ground to a very fine power, sand, and gravel of a particular size range (aggregate). To prepare the dry concrete pre-mix for use in construction projects, a pre-determined volume of water is added to the dry pre-mix, and thoroughly mixed with the water to form a thick, viscous slurry which may then be poured into formworks at a construction site. The water chemically reacts with the constituents of the Portland cement, typically anhydrous tricalcium silicate, tricalcium aluminate, dicalcium silicate and tetracalcium aluminoferrite, to form a solid gel of needle-like crystals that comprise an interlocking framework which binds the aggregate and sand particles. When these reactions have been driven to completion, in a process referred to as curing, the concrete slurry is transmitted into a substantially strong, stone-like solid consisting of a matrix of Portland cement crystals interspersed with aggregates and sand particles.
The strength, durability and appearance of finished or cured concrete depends strongly on the thoroughness with which the pre-mix ingredients and water are mixed prior to pouring the concrete slurry. Therefore, most concrete is mixed by a machine, either by a motor driven drum at a work site or in central batching and mixing plants, with the fresh concrete being taken to a job site in a revolving drum mounted on a ready-mix truck. However, small batches of concrete are mixed by hand on an increasingly frequent basis, by homeowners, handymen and do-it-yourselfers. For these uses, building supply stores and similar establishments sell dry concrete pre-mix in paper bags, typically containing 60 or 90 pounds of material.
A customary method for utilizing individual bags of dry concrete pre-mix for small jobs includes first pouring a pre-determined quantity of water into a mixing container such as a wheelbarrow or shallow rectangular mixing tray. Next, a bag of dry concrete pre-mix is opened, and the contents of the bag dumped into the mixing container, on top of the water. The water and dry concrete pre-mix, the latter consisting of finely powdered Portland cement, sand, and aggregate, the latter usually consists of gravel of a particular size range, are then mechanically worked to thoroughly mix all four component ingredients. The most commonly used method for mixing small batches of concrete consists of repeatedly inserting the blade of a long handled implement such as a hoe into the material in the mixing container, and drawing the hoe repeatedly through the material to intermingle dry concrete pre-mix ingredients with water in the container.
Existing hoes used for hand mixing concrete have a construction similar to that of common long-handled garden or agricultural hoes. One type of hoe which is widely marketed and used for mixing concrete is substantially similar in construction to the Plasterers Hoe disclosed in Canfield, U.S. Pat. No. 317,502, patented on May 12, 1885. That hoe has a generally rectangularty-shaped, laterally elongated blade, the central portion of which is reinforced by a rib which is a forward extending, thickened portion of a tang and which is attached to the front of the blade. The blade is provided with a pair of identical circular perforations or apertures laterally spaced apart and equidistant from a vertical plane passing centrally through the rib. The upper edge of the blade has a pair of laterally spaced apart, arcuately curved convex protrusions concentric with the two apertures through the blade.
The intended function of Canfield""s hoe is to mix dry plaster, a homogeneous material consisting essentially of powdered calcium sulphate (Gypsum), with water to form a viscous paste suitable for application to structure wall lathing of buildings, and similar such uses. However, as described above, concrete pre-mix is a heterogeneous, multi-phase conglomeration of Portland cement powder, sand, and gravel, all of which must be thoroughly intermixed with water to prepare the concrete for pouring. Therefore, while presently used concrete mixing hoes provided with a pair of laterally spaced apart circular holes through the blade seem to permit the hoe blade to be more readily drawn through a vicious multi-phase mixture of water and dry concrete pre-mix, mixing concrete with existing hoes of this type is still a strenuous, tedious task.
Subsequent to Canfield""s disclosure, a number of U.S. patents have issued for hoes intended to mix mortar, or perform agricultural tasks. These include:
Dickson, U.S. Pat. No. 565,379, Aug. 4, 1896, Mortar Hoe: Discloses a mortar hoe having an improved blade intended to cut and mix mortar finer, more uniformly and with greater ease then common mortar hoes. The blade has through its thickness pairs of vertically elongated slots located on each side of the vertical center of the blade, and a pair of horizontally elongated slots equidistant from the vertical center and extending over the vertical slots. The upper edge of the blade is arcuately curved to form a pair of convex humps spaced laterally apart and equidistant from the vertical center and, the humps form therebetween a concavely curved groove or trough.
Anderson, U.S. Pat. No. 865,150, Sep. 3, 1907, Mortar Mixer Or Hoe: Discloses a mortar hoe having a generally rectangularly-shaped blade provided in one embodiment with two rows of vertically elongated, generally rectangularly-shaped perforations, and in another embodiment with three rows of generally square-shaped perforations.
Holmes, U.S. Pat. No. 1,127,440, Feb. 9, 1915, Mortar Hoe: Discloses a mortar hoe having a generally rectangularly-shaped blade provided with pairs of vertically elongated perforations located equidistant from the vertical center line of the blade, each of the perforations formed from a vane angled outwardly from the plane of the blade.
Birn, U.S. Pat. No. 1,167,971, Jan. 11, 1916, Mixing Hoe: Discloses a mixing hoe having a generally rectangularly-shaped blade comprising an open frame provided with laterally spaced apart, vertically elongated, rectangularly-shaped apertures each bordered by a vertically elongated mixing bar having a diamond cross section and having longitudinally extending sharp edge portions disposed forwardly and rearwardly with respect to the plane of the blade.
Beymer, U.S. Pat. No. 1,185,581, May 30, 1916, Garden Implement: Discloses a garden implement comprising a hoeing blade having two or more meeting edges sharpened for cutting and an angular shank member having one of its ends connected to the upper end of the blade and its other end projecting rearwardly in a line intersecting the blade at the axis of the working resistance.
Rhomberg, U.S. Pat. No. 1,286,779, Dec. 3, 1918, Hoe: Discloses a garden hoe including a handle and a substantially flat blade having horizontal sets of forwardly and rearwardly extending cutters folded out from rectangular perforations arranged in a horizontal row. The forwardly extending set of triangular cutters have their upper edges horizontal and their lower edges oblique, while the rearwardly extending set of triangular cutters have their upper edges oblique and lower edges horizontal.
Clark, U.S. Pat. No. 1,387,883, Aug. 16, 1921, Hoe: Discloses a hoe including a blade having the shape of a sector of a circle with the apex of the sector pointing downwardly.
Miljan, U.S. Pat. No. 3,116,796, Jan. 7, 1964, Multi-Purpose Agricultural Hand Tool: Discloses a hoe-like agricultural hand tool including a substantially triangularly-shaped blade having a downwardly pointed, curved apex, the blade being angled rearwardly from a plane perpendicular to the axis of the straight handle.
Bojar, PCT/US95/08698, Jul. 13, 1995, Adjustable Pitch Garden Hoe Tool: Discloses an adjustable pitch garden hoe tool.
Solomon, D 35,242, Oct. 29, 1901, Hoe: Discloses an ornamental design for a hoe having a triangular-shaped blade angled forward from a handle.
Pole, D 246,498, Nov. 29, 1977, Blade For A Mortar Hoe: Discloses an ornamental design for a mortar hoe having a flat blade curved rearwardly from a shank fastened to a straight handle, and an extruded mesh surface forming an array of rhomboidly-shaped apertures.
None of the prior art patents known to the present inventor and listed above provide a solution to two problems encountered in hand mixing dry concrete premix with water using prior art implements; specifically, the substantial physical exertion and time required by the use of prior art mixing implements. The present invention was conceived of as a solution to the aforementioned problems.
An object of the present invention is to provide an improved hoe for mixing dry concrete pre-mix, consisting of Portland cement, sand, and aggregate such as gravel, with water to form a uniformly mixed slurry suitable for pouring into formworks or use in other construction applications.
Another object of the invention is to provide an improved concrete mixing hoe which requires a relatively small force to push or pull the hoe through a viscous multi-phase slurry consisting of concrete premix and water.
Another object of the invention is to provide an improved concrete mixing hoe which requires a relatively short time duration to mix a batch of liquid concrete to a desired degree of uniformity.
Another object of the invention is to provide an improved concrete mixing hoe having an elongated handle provided with a rear hand grip portion and a blade depending generally perpendicularly downwardly from the front end of the handle, the blade having in plan view a shape approximating that of an isosceles triangle with a downwardly pointing vertex.
Another object of the invention is to provide an improved concrete mixing hoe having a blade which in front elevation view has the shape of an isosceles triangle with a downwardly pointing, arcuately convexly shaped vertex.
Another object of the invention is to provide an improved concrete mixing hoe having a blade which has a transversely disposed upper or base edge.
Another object of the invention is to provide an improved concrete mixing hoe having a blade which has in front elevation view a shape approximating that of an inverted isosceles triangle and having through its thickness dimension at least a first hole centered on a vertical center line of the blade and located proximate the vertex.
Another object of the invention is to provide an improved concrete mixing hoe having a blade which has in front elevation view a shape approximating that of an inverted isosceles triangle and having through its thickness dimension a first lower hole centered on a vertical center line of the blade and located proximate the vertex, and a second, upper hole centered on the vertical center line and located above the first hole.
Another object of the invention is to provide an improved concrete mixing hoe having a blade which has in front elevation view a shape approximating that of an inverted isosceles triangle and having through its thickness dimension a plurality of holes arranged vertically along a center line of the blade, each hole being of larger diameter than the one below it.
Various other objects and advantages of the present invention, and its most novel features, will become apparent to those skilled in the art by perusing the accompanying specification, drawings and claims.
It is to be understood that although the invention disclosed herein is fully capable of achieving the objects and providing the advantages described, the characteristics of the invention described herein are merely illustrative of the preferred embodiments. Accordingly, I do not intend that the scope of my exclusive rights and privileges in the invention be limited to details of the embodiments described. I do intend that equivalents, adaptations and modifications of the invention reasonably inferable from the description contained herein be included within the scope of the invention as defined by the appended claims.
Briefly stated, the present invention comprehends an improved hoe which is particularly well adapted to efficiently, thoroughly and easily mix dry concrete pre-mix with water to form a thick paste or slurry of liquid concrete preparatory to pouring the liquid concrete into a form or using the liquid concrete in other such structural or construction applications.
A preferred embodiment of a concrete mixing hoe according to the present invention includes a conventional elongated, straight handle adapted to be grasped at the rear end thereof by a person""s hands. Attached to the front end of the handle is a blade which depends substantially perpendicularly downwards from the longitudinal axis of the handle. According to the present invention, the blade is made of rigid, durable plate stock such as {fraction (3/32)}inch-thick steel plate, and has a novel shape. Thus, according to the present invention the blade is disposed in a plane perpendicular to the handle, and has in front and rear elevation views a shaped approximating that of an inverted isosceles triangle, with the base of the triangle consisting of generally horizontally disposed upper edge of the blade, and a downwardly depending vertex. The downwardly pointing vertex of the blade is preferably radiused to form a convex, arcuately curved surface. Also, the upper edge of the blade may optionally be arcuately convexly curved rather than straight.
According to the present invention, the blade has through its thickness dimension a plurality of vertically spaced apart holes, centered on a vertical center line of the blade. These holes are preferably of stepped diameters, including a first, lower hole having a first diameter located near the vertex of the blade, and at least a second hole of larger diameter located between the first hole and the upper edge wall of the blade. With this novel construction, the curved vertex and wedge shape of the blade enables the blade to be easily pressed downwardly into dry concrete pre-mix and underlying water loaded into a mixing container such as a wheelbarrow or mixing tray. Moreover, the smaller diameter lower hole through the blade permits the blade to be pulled or pushed through a multi-phase slurry in which the lower component is substantially liquid, i.e., water, the latter passing readily through the smaller hole with little resistance. Additionally, the larger hole provided in the upper portion of the blade permits ready passage of aggregate such as gravel therethrough with little resistance. Therefore, as the blade is pulled or pushed through the heterogenous, multi-phase combination of dry concrete pre-mix and water, the triangular shape of the blade creates a deep, V-shaped channel or furrow in the materials, which is quickly filled in by materials falling into the furrow under the force of gravity, as the blade passes through. This action results in efficient folding or intermixing of material at various heights within the container. Importantly, the stepped diameter holes through the blade of the concrete mixing hoe according to the present invention substantially reduces the force required to pull or push the hoe through a concrete/water slurry, as compared to prior art mixing hoes.
Also, the convex, arcuately curved vertex of the blade according to the present invention functions as a bearing surface, allowing the blade to be inserted into a slurry sufficiently deeply to contact the bottom wall of the container, and still be drawn or pushed longitudinally with less drag force than prior art hoe blades having flat bottom edges. Thus, the novel construction of a concrete mixing hoe according to the present invention enables dry concrete mix to be thoroughly mixed with water to form a slurry ready for use with greater ease and in less time than prior art devices.